Vinculin is large protein of MW 120 KDa, of unknown structure, which plays a central role in the assembly of focal adhesions. These are macromoleular complexes found at cell-matrix junctions, which provide a structural and functional link between the extracellular matrix and the actin cytoskeleton. Much is known about the binding activities of vinculin in vitro, and the field is well poised to benefit from structural data at atomic resolution, which would elucidate the structural basis of focal adhesion assembly and regulation